The present invention relates to an improved extendible telephone having a body casing or main casing incorporating a receiver and an operation casing or auxiliary casing incorporating a transmitter and dial keys.
Various kinds of telephones extensively used today include a radio telephone to be used while in movement and a cordless telephone to be used only in a relatively narrow range, e.g. , in an office or a home. A portable radio telephone, for example, should preferably be small size and light weight since it is carried by the user. It is a common practice with this kind of telephone to connect an auxiliary casing having a transmitter foldably or openably to a main casing having a receiver and dial keys by a hinge mechanism. To use the telephone, the user unfolds or opens the auxiliary casing away from the main casing to a position where a desired angle for conversation is set up and the receiver and transmitter are spaced apart by a desired distance. While the telephone is not used, it is put in, for example, the user's pocket with the auxiliary casing folded or closed. Such a foldable telephone is disclosed in, for example, U.S. Pat. No. 4,897,873 (Beutler et al) and Japanese Patent Laid-Open Publication (Kokai) Nos. 212052/1989 and 159159/1990. The conventional foldable telephone, however, has a drawback that the hinge mechanism is exposed to the outside of the main and auxiliary casings since it cannot be readily incorporated in the main casing or the auxiliary casing, limiting the design freedom. In addition, the hinge mechanism is relatively bulky since it has to have a sufficient mechanical strength, obstructing the decrease in the size and weight of the telephone while degrading portability. Moreover, wirings between the main and auxiliary casings should be set up by way of the hinge mechanism and are, therefore, troublesome to in turn complicate the assembly of the telephone.
An extendible telephone, as distinguished from a foldable telephone, is also conventional. In an extendible telephone, an auxiliary casing having a transmitter and dial keys is slidably mounted on a main casing having a receiver by a guide mechanism. To use this kind of telephone, the auxiliary casing is slid via the guide mechanism to an extended position where the receiver and the transmitter are spaced apart by a desired distance. While the telephone is not used, the auxiliary casing is contracted to a position suitable for the telephone to be put in, for example, the user's pocket. However, since the extendible telephone has the guide mechanism having guides and guide channels thereof exposed to the outside of the main and auxiliary casing, not only the appearance is degraded, but also the design freedom is limited. The guide mechanism causes the guides and guide channels to slide on each other during extension and contraction, causing the main and auxiliary casings to wear. It follows that at least the contacting portions of the telephone, i.e. , the main and auxiliary casings have to be made of a material which are high slidable and resistive to wear, increasing the cost of the telephone. Furthermore, replacing the main and auxiliary casings and due to wear is troublesome and further increases the cost of the the telephone.